The invention pertains to a retaining device for holding, guiding and self-actuated releasing of an assembly part, such as a nut or another element in a device for bringing the assembly part to a plate-shaped component, or in another device for precise conveyance of the element.
A retaining device of this type for a punching mechanism for pressing a nut into sheet metal is known for example from DE-PS 1,254,940 and is widely used in practice. In this punching mechanism the sliding unit forms the press plunger, which is mounted to a housing securely joined to the upper part of the press, and this sliding unit extends into the channel of the guide piece in order to feed the nut through the channel to the work position and to press it into the sheet metal resting on a bottom die. The guide piece is moved laterally up to a guide stud located off-center with respect to the housing; said guide stud can slide relative to the upper part of the press against the pretension of the helical compressed springs. The retaining device consists of two retaining catches that are articulated at the guide piece in the region of the feeding opening and block any downward motion of the nut, until the plunger moves downward and thereby pivots the two retaining catches into their open position. The nut then moves in the channel from the initial position down to the working position without being guided and positioned, except by the channel walls.
Therefore misalignments, slanted positions or other positioning inaccuracies can occur that result in corresponding errors during the assembly process. Additional disadvantages of the known device are that they require a relatively large manufacturing effort, a large number of individual parts and also a considerable space requirement.